Round belt



.May 6, 1941- c. w; YELM Erm. 2,240,735

v ROUND BELT y Filed Feb. 24, 1940 32 CHARLES WYEl-n 4W ANTONE EREzNlceK FIG-8 INVENTOR ATTORNEY.

Patented May 6, 1941 ROUND BELT Charles W. Yelm and Antone F. Rezuicek,Denver,

Colo.,

assignors to The Gates Rubber Company,

Denver, Colo., a corporation of Colorado Application February 24, 1940,serial No. 320,568

(ci. 'a4-zas) 11 Claims.

This invention` relates to improvements in round belts of the typeconstructed from rubberized cord and rubberized woven fabric.

It is quite common to construct endless belts having a core ofsubstantially inextensible cords enclosed in a covering of bias Vcutrubberized fabric. In such belts the fabric is invariably cut on aforty-live degree bias. Such belts operate very nicely in pulleys havingV-shaped grooves and after they have been in operation for acomparatively short time the sides flatten where the belts come intocontact with the sides of the grooves. The deformationis caused by therepeated pressure applied to the same portions of the belt surface bythe sides of the pulley grooves. Such belts wear unequally because thewear is not distributed over the surface.

It has been found that a round belt will wear longer if it is slowlyrotated about its axis during operation because the outer surface willthen wear equally atl all points, the belt will retain its circularcross sections, and the strains due to the constant flexing of the beltin its travel about the pulleys will be distributed to all parts of thebelt.

It is the object of this invention to produce an endless round belt ofsuch construction that the forces transmitted by the belt will producein the belt itself torsional forces which cause the belt to turnautomatically about its axis during operation.

The above object is attained by the simple expedient of so positioningthe rubberized fabric that the warp and the woof will make unequalangles with the axis of the belt thereby setting up unequal torsionalstrains when the belts are subjected to tension, as distinguished fromthe ordinary belts in which the covering strips of rubberized wovenfabric are so positioned that the warp and woof make equal angles withthe longitudinal elements of the belt.

Having thus explained the objects yof the invention and brieflydescribed the same, the invention will now be described in detail, andfor this purpose reference will be had to the accompanying drawing inwhich the invention has been illustrated and in Which- Figure 1 is atransverse section showing a belt of the type to which this inventionrelates.

Figure 2 is a View showing Athe manner in which the material isassembled on a drum.

Figure 3 is a section' taken on line 3-3 of Fig. 2.

Figure 4 is a diagrammatic representation of a round belt havingrubberized fabric covering cut on a. forty-ve degree bias.

Figure 5 is a view similar to that shown in Fig. 4 and shows a coveringcut on a bias less than forty-five degrees.

Figure 6 is a diagram showing the distorting forces developed in a wovenfabric in which the warp and the woof make different angles with thedirection of the force.

Figure '7 is a top plan view of a belt showing the same in place onspaced pulleys, the direction of the warp and Woof being designated bylines angularly related to the axis of the belt; and

Figure 8 is a cross section of a belt, constructed as shown in Fig. 4,and shows the flattened sides of the belt.

In Fig. 7 of the drawing, reference numeral I0 designates the axlesabout which pulleys I I rotate and reference numeral I2 designates anendless round belt which is applied to the pulleys.

The arrow I3 indicates the direction in which the belt moves while arrowI4 indicates the direction of the maximum torsional strain.

In Figure l, reference vnumeral I5 indicates a heavy cotton cord that issurrounded by one or more layers I6 of rubberized cord. Wound spirallyabout the core thus formed is a strip I1 of woven rubberized fabric.This strip is cut on a bias in such a manner that the angle between thelongitudinal axis of the strip and the warp and woof are unequal as willbe hereafter more .fully explained.

The belt is constructed in the manner illustrated in Figs. 2 and 3 inwhich reference numeral I8 designates a cylindrical drum mounted forrotation on an axle I9. The diameter of the drum is determined by thesize of the belt to be made thereon. A strip of woven rubberized fabricI1, cut on the bias, is wound around the drum in the manner shown. Alongone edge of fabric I1 and slightly overlapping the same is a narrowstrip 20of rubberized cord fabric and overlapping this is another -strip2i of similar rubberized cord fabric. The cords in strip 2i arepreferably somewhat finer than those in strip 20.

Wound around the edge of strip 2|` is a cotton cord 22. When theelements just explained have been applied to the drum the operatorstarts rolling the cord 22 towards the right, when viewed less belts andno novelty is claimed for the method.

It has been explained above that the effects sought by this inventionare due to the specific relation between the directions of the warp andwoof in the woven fabric strip I1 and the axis of the belt.

In Fig. 2 the warp has been'designated by lines 23 and the woof by lines2l which extend at right angles to line 23. The longitudinal axis ofstrip i1 has been indicated by line 25-25. 'I'he angle between the axisof the strip and the warp 2l has been designated by w and thecorresponding angle between the axis 25-25 and the woof has beendesignated by reference connection at. It will be seen that the angle wis smaller than angle 1:, whereas in the ordinary belts the stripcorresponding to strip I1 is so cut that the-axis 25-25 makes anV angleof 45 degrees with both the warp and the woof.

Referring now to Fig. 4, reference numeral 26 designates a short sectionof round 1belt While reference numerals 23 and 24 indicate respectivelythreads in the warp and the Woof of the strip. In this embodiment thewarp and wool! both make an angle of 45 degrees with a diametrical planeof the belt and consequently if the belt is subjected to a tension,indicated by reference character P, there will be no tendency for thebelt to turn about its axis since the warp and woof both exert equalamounts of torsional strains and since these forces or strains act inopposite directions they neutralize each other.

In Fig. v5 a belt 26a has been shown which is similar to that shown inFig. 4, with the exception that the angle between the warp 23 and theaxis of the belt, which angle has been designated by w, is less than thecorresponding angle between the woof 24 and the axis of the belt.'IheJatter angle has been designated by reference character z.

InFig. 5 the ends of the belt have been shown as secured in caps 21. Thecap at the left end is presumed to be attached to a stationary member 28so that it cannot rotate. 'Ihe cap 21' at the right hasbeen shown asprovided with a headed pivot pin 29 that passes through a suitableopening in link 30 in such a way that relative rotation can take place.It is presumed that a force P is applied to link 30 whereby the belt issubjected to tension. When the belt is put under tension the tendency isfor the helically extending warpthreads 23 to straighten. Since` thepitch of the warp is greater than the pitch of the woof the torsionalforce exerted by the warp will exceed the corresponding force exerted bythe woof'and as the result the belt will twist downwardly on the nearside, as indicated by the arrow 3i.

' In Fig. 6, a diagram has been shown which will show the deformingaction of a tensional force applied to a strip of woven fabric cut on abias in such a way that the angle between the warp 23 and the directionof the tensioning force is smaller than the angie between the woof 2land the direction of the tensioning force. When such a strip of fabricis subjected toa force tending to stretch it, the lower right-handcorner will move downwardly, as indicated by arrow lia. If such a stripcovers a round .belt it is evident that the belt will tend to turn aboutits axis when it is exerting a force as it does when transmitting power.

Referring now to Fig. 7 in which a belt constructed in the mannerdescribed has been applied to two spaced pulleys Ii, it will be evidentthat when the belt is under tension the unequal torsional force abovereferred to will twist the belt slightly. As the belt is moving towardsthe right, when viewed as in Fig. 7, the slight twisting produced by theunequal torsional strains will continue as long as the belt isoperating, with the result that the belt will slowly turn about its axisthereby distributing the wear uniformly over the entire outer surface.

When a belt is constructed in the usual way with the warp and Woofmaking equal angles with the axis of the belt `\there is no tendency forthe belt to twist and to rotate, and' after it has been in operation fora comparatively short time the sides that contact with the sides of thegrooves in the pulleys will become flattened, as indicated by referencenumeral 32 in Fig. 8. In such a belt the unequal stretching between theinner and outer surface of the belt will always be borne by the sameparts of the belt and as a result the belt will fail quicker than if itwere rotating about its axis during the operation.

A belt constructed in the manner above described wiil continue to be ofcircular shape and the strains will be distributed uniformly over thematerial ofthe belt.

In the example illustrated the outer covering, which has been designatedby reference numeral Il, has been shown as formed from woven rubberizedfabric and it is believed that this is the most desirable material to beemployed. It is possible to obtain the same turning eiiect by employingstrips of cord fabric wound helically and in opposite directionsadjacent layers being wound at a different pitch.

It is also possible to obtain unequal torsional force in a beltconstructed as shown in Fig. 4 by twisting the belt before it isvulcanized whereby the equilibrium of force between the warp and theWoof will |be disturbed; such a belt. however, will not continue torotate in the same direction but will oscillate through a comparativelysmall angle.

Although the belt has been shown as provided with a cord core this isnot an essential element for the purpose of obtaining the rotary actionabove described.

In the above description the warp 23 has been described as making thesmaller angle with the axis of the belt but it is to be understood thatit is immaterial whether the worp or the Woof' from one-eighth toone-sixteenth of the strength of the solid belt. A belt working undernormal conditions is never strained beyond the elastic limit of thematerial and therefore the` cordsA comprising the core, the weft and theWoof always possess some residual elasticity.

Having described the invention, what is claimed as new is:

1. An endless, self-turning, round belt .having -a central core of cordsand a ycovering of bias cut fabric, the belt body having incorporatedtherein two groups of oppositely wound helically extending tensionmembers, one group having a different pitch than the other whereby aresultant torque is produced which tends to twist the belt in onedirection when it is subjected to a Stretching force.

2. An endless, self-turning, round belt having a central cord coresurrounded by rubberized fabric, the4 body having incorporated thereinan unbalanced assembly of oppositely wound groups of helically extendingtension members which tend to straighten when the belt is subjected toan extending force thereby producing unequal oppositely acting torqueswhose resultant tends to twist the belt in one direction and causes itto rotate about its axis during operation.

3. An endless, self-turning, round belt having a central cord coresurrounded by rubberized fabric, the body having incorporated therein'at least two sets of oppositely wound helically extending tensionmembers, the members of each set having different pitch angles wherebyopposed torque forces are produced when the belt is subjected totension, the resultant of said torque forces tending to twist thebeltabout its axis and cause it to rotate during operation.

4. An endless, self-turning, round belt having a core surrounded by arubber containing body and an outer cover of |bias cut fabric, means forproducing a twisting force in the belt while it is operating, said meanscomprising at least two sets of oppositely wound, helically extendingcords having different pitch angles and which tend to straighten whenthe ibelt :is tensioned whereby a resultant torque is produced whichtwists the belt through a small angle, whereby the belt willI rotatewhen operating.

5. An endless, self-turning, round belt having a Wall formed from atleast two groups of threads -extending helically about its axis, thegroups extending in opposite directions, the threads that extend in onedirection having a greater vpitch than those that extend in the otherdirec- 6. An endless, self-turning, round belt having.

an outer wall comprising at least two groups of `rubberized threadswound helically, one group each group being parallel and the threads ofthe two groups being wound'at different pitch angles, whereby unequaltorsional strains will bc set up in the belt when it is subjected totension. v

7. An endless, self-turning, round belt having an outer layer ofrubberized woven fabric in which`the warp and the woof make differentangles with respect to a diametrical plane of the belt, whereby unequaltorsional forces will be set up in the belt when it is subjected totension.

8. An endless. self-turning, round belt having a central core oflongitudinally extending cords surrounded |by a spirally wound layer ofbias cut rubberized woven fabric in which the warp and the Woof extendhelically around the belt and are inclined at different angles to thelongitu- 1o. An endless, self-turning; round beit having.

a core of substantially parallel cords; and a covering formed from atleast two groups of parallel rubberized threads extending helicallyaround the core, the threads of the groups extending in oppositedirections, and at different pitch angles, whereby unequal torsionalstrains will be produced in the belt when it is subject to strain. I y

11. An endless, self-turning, round belt having a core of longitudinallyextending parallel cords, and an outer wall formed fromrubberized wovenfabric rolled spirally about the core, the fabric being formed intostrips., the axis of the strip making unequal angles with the warp andthe Woof, whereby unequal torsional forces will be produced in the beltwhen it is subjected to tension.

CHARLES W. YELM.

ANTONE F. REZN'ICEK.

